1. Field of the Invention
The present invention relates to a liquid ejection head that ejects a liquid, an ejection method that a liquid is ejected from the liquid ejection head, and a printing apparatus that employs the liquid ejection head to eject a liquid for printing.
2. Description of the Related Art
An ink ejection system that employs heating resistor elements has been commonly employed as a liquid ejection method for an ink jet printing apparatus. In this type of ink jet printing apparatus, bubbles are generated on the heating resistor elements, and thereby ink is ejected by a print head to perform printing. When printing is performed by this type of ink jet printing apparatus, cavitation occurs when bubbles generated on the heating resistor elements have become smaller and disappeared. The occurrence of cavitation might adversely affect the service life of the heating resistor elements.
A liquid ejection head is disclosed in Japanese Patent Laid-Open No. 2002-321369, wherein in order to reduce the adverse effect for each heating resistor element due to cavitation, the center of an ink flow path is arranged offset from the center of the heating resistor element in a direction perpendicular to the direction in which ink is to be supplied. Since the liquid ejection head is arranged in this manner, a bubble becomes smaller and disappears at a location apart from the heating resistor element. As a result, the occurrence of cavitation on the heating resistor element can be prevented, and the adverse effect on the service life of the heating resistor element can be reduced.
However, according to the arrangement of the print head disclosed in Japanese Patent Laid-Open No. 2002-321369, it is required that space for bubble generation chambers be prepared to provide a bubble break position offset from the heating resistor element in a direction perpendicular to the direction in which ink is to be supplied. Therefore, the space required for the individual bubble generation chambers is increased, and ejection ports can not be arranged with high density. Accordingly, the size of the liquid ejection head would be increased.